This invention relates to a process and system for enhancing the detection of larvae or worms in shelled nuts for separation and removal therefrom.
The pecan weevil Curculio Caryae, is a late-season pest of pecans. The weevil appears in late August and early September. After the nut kernals begin to form, the female chews a hole in the shell and deposits her eggs in little pockets in the nuts. Creamy, worm-like larvae or grubs hatch from the eggs and feed inside the nuts during the fall. When they reach maturity, the grubs chew a hole in the shell, emerge from the nut and drop to the ground in late fall and early winter. They burrow in the soil and transfer to pupae. The adults appear during the summer, following pupation and the cycle is repeated.
The weevil is controlled to some extent by insecticides, however, it has been impossible to completely eliminate the pecan weevil whereby pecans harvested have the grubs or larvae therein. The grubs or larvae must be removed from the shelled pecans for successful marketing thereof. For purposes of this application, the grubs or larvae also will be referred to as worms.
Pecan processors have employed workers to hand pick the larvae or grubs out of the shelled pecans. When carried out on smaller broken pecan pieces, which are also processed for sale on the market, the hand picking process must be repeated a number of times in order to satisfactorily remove most of the worms. This is due to the fact that the larvae has a color which is about the same as the pecan meat and it is very difficult to distinguish the larvae from the meat of the broken pieces particularly since the size of the larvae is about the same as that of the broken pecan pieces. As can be understood each time the pecans are repicked, the processing cost increases.
Ultraviolet light has been used in the hand picking process and has been tried in sorting machines to enhance the detection and separation of the larvae. When illuminated or irradiated with ultraviolet light, the larvae fluoresces whereas the skins of the pecans do not fluoresce. This has improved the sorting or separating process, however, it still results in poor separation quality since the exposed meat of the broken pecan pieces also fluoresces when illuminated with ultraviolet light. Thus, even with ultraviolet light, it is difficult to distinguish the larvae from the pecan meat, both of which fluoresce under ultraviolet light. This results in many larvae being missed in the hand picking process and many pecan pieces being rejected along with the larvae in the sorting machines. In the hand picking process, even with ultraviolet light, the pecans must be repicked (thereby increasing the processing cost) to satisfactorily remove most of the worms.